WIS 07.07 Air Volume Gauge, Air Mass Gauge

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Reference: WIS 07.07 Air Volume Gauge, Air Mass Gauge

Description - MAF

The Mass Air Flow (MAF) Sensor is also known as the Air Volume Gauge or Air Mass Gauge.

The MAF contains a hot wire sensor. For a complete description refer to:


W220 Mass Air Flow (MAF) Sensor.JPG

This is what a MAF looks like courtesy of German Star.

W220 MAF Sensor Element Courtesy of German Star.JPG

Self Cleaning Function - MAF

One BenzWorld Member stated that the Bosch MAFs have a cleaning cycle. During this cycle, the current is briefly increased to the hot wire sensor and this increases the temperature to something like 1000F. This is akin to a self cleaning oven.

Issues - MAF

A commercial cleaner will remove oil and such deposits, but in the case of the Bosch MAF units, the deposit is probably more like a hard scale caused by deposits baking on.

DIY - Replace MAF

The following video shows how to replace the MAF housing:

MAF Housing Relacement (By Masood)

The M-B designers knew that the MAF will foul over time and included programming that allows it to adapt to a changing reading. When this adaptation gets out of range, we get the typical mixture codes - such as P0170/3. Dealers apparently have the ability to check the degree of "adaption" whereas all we can read with our OBD II meters, is the codes.


It is possible to re-use your MAF housing and just buy the Bosch insert eg for $139 from Germanstar.net. That is the cheapest in the current market.

However the MAF is held in place with Torx Security Screws which have a dimple in the center of the screws and a special driver is needed.

MAF Security Torx Screw Driver.JPG

See article on cleaning by BenzWorld Member Check Codes.


There are heaps of other article on cleaning and replacing the MAF.

To Be Completed.